VitalsCentral

Furosemide

Lasix

FDA ApprovedCardiovascular AgentsDiuretics
Half-life: Approximately 1.5-2 hoursPregnancy: Category C

Overview

Furosemide is a potent loop diuretic used to treat fluid overload and edema associated with heart failure, renal disease, and hepatic cirrhosis, and to manage hypertension.

Indications

  • Edema associated with heart failure
  • Edema of renal or hepatic origin
  • Hypertension
  • Acute pulmonary edema

Contraindications

  • Anuria
  • Severe electrolyte depletion
  • Hypersensitivity to sulfonamides

Classification

Cardiovascular AgentsDiureticsCardiovascular SystemRenal System

Mechanism of Action

Inhibits the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle, blocking reabsorption of sodium and chloride and producing a strong diuresis.

Pharmacodynamics

Produces rapid, dose-dependent diuresis and natriuresis, reducing preload and relieving edema. Also increases excretion of potassium, calcium, and magnesium.

Pharmacokinetics

Absorption
Variably absorbed orally with bioavailability around 50%.
Distribution
Highly protein bound; distributes primarily in the extracellular fluid.
Metabolism
Undergoes limited hepatic and renal glucuronidation.
Excretion
Excreted mainly unchanged in urine via glomerular filtration and tubular secretion.
Half-life
Approximately 1.5-2 hours
Bioavailability
Approximately 50% (oral)
Protein Binding
Approximately 95%

Dosage

Typical dosage: 20-80 mg per dose, titrated to response

Available Forms

  • Tablet
  • Oral solution
  • Injection

Side Effects

Common

  • Increased urination
  • Hypokalemia
  • Dizziness
  • Dehydration

Serious

  • Severe electrolyte imbalance
  • Ototoxicity
  • Acute kidney injury from volume depletion

Rare

  • Interstitial nephritis
  • Blood dyscrasias

Drug Interactions

Digoxinmajor

Diuretic-induced hypokalemia increases the risk of digoxin toxicity and arrhythmias.

Lithiummajor

Reduces renal lithium clearance, raising serum lithium levels and the risk of toxicity.

Warnings

⚠️BLACK BOX WARNING

Furosemide is a potent diuretic that, if given in excessive amounts, can lead to profound diuresis with water and electrolyte depletion. Careful medical supervision is required, and dose and dosing schedule must be individualized.

Pregnancy

Category C

Toxicity

Overdose causes dehydration, electrolyte depletion, hypotension, and circulatory collapse.

Overdose

Treat with fluid and electrolyte replacement and supportive care; monitor renal function and electrolytes.

References

Looking for patient-friendly information? Visit RemedyDoor for easy-to-read guides about this medication.